As is known in the art, detection of encoded signals, such as a “wake up” signals, is needed to activate remotely deployed, unattended wireless sensing networks. More particularly, there are systems that require zero or near zero power consuming wake-up receivers to greatly extend the lifetime of such remotely deployed unattended wireless sensing networks, which have the capability to continuously and passively monitor the environment and detect such wake-up signals.
As is also known in the art, in addition to requiring that the ultra-low power consumption, these wake-up signal receivers also require a high wake up signal detection probability in the presence of background noise.
One such wake-up signal receiver stores in a digital memory a digital code representative of a code embedded in the wake-up signal. The receiver includes digital processing circuitry, including for example a correlator, and timing circuitry response to a source of clock pules, to detect whether signals received by the receiver have embedded therein a code which correlates with the code stored in the memory. While such a receiver is able to detect the wake-up signal, it requires relatively high power consuming digital circuitry.